1. Field of the Invention
This invention relates to a flow rate measuring apparatus for measuring the flow rate of a cooling medium flowing through a gas turbine moving blade, within which a hollow passage is formed for introduction of the cooling medium, a moving blade support apparatus in the flow rate measuring apparatus, and a moving blade support jig in the moving blade support apparatus.
2. Description of the Related Art
A gas turbine has gas turbine moving blades in a circumferential direction of a rotor. In the gas turbine, a rotating shaft is rotationally driven by a combustion gas flowing between the adjacent gas turbine moving blades to drive a compressor and a generator, for example.
A high temperature combustion gas is introduced into the gas turbine, and the gas turbine moving blades and gas turbine stationary blades at a preceding stage are exposed to high temperatures. Thus, cooled blades, within which hollow passages are formed for entry of a cooling medium, may be used as gas turbine moving blades at an inlet of the gas turbine.
The passages of the gas turbine moving blade are supplied with the cooling medium (compressed air) through a cooling medium inflow port formed at a bottom surface of the site of embedding of the blade in the rotor (see, for example, Japanese Unexamined Patent Publication No. 2000-12205).
In the gas turbine moving blade, measurement for finding whether a predetermined amount of the cooling medium flows through the passages of the gas turbine moving blade is made at completion of a new blade or during periodical inspection for quality control.
In this case, the gas turbine moving blade is mounted on a flow rate measuring device, and air or the like is flowed through the cooling medium inflow port so that its flow rate is measured, whereby it is evaluated whether a predetermined amount of the cooling medium flows through the passages of the gas turbine moving blade.
Mounting of the gas turbine moving blade on the flow rate measuring device is performed, such that the gas turbine moving blade is attached to an air inflow portion, with a sealing plate member made of rubber or the like, as a moving blade support jig, being interposed at the cooling medium inflow port (the bottom surface of a portion of the moving blade embedded in the rotor), in order to prevent air supplied from leaking to the outside. In the sealing plate member made of rubber or the like, a hole of the same shape and at the same location as the cooling medium inflow port is formed so that air does not escape outside and the flow of air is not impeded.
That is, as shown in FIG. 7, a gas turbine moving blade 81 has a Christmas tree-shaped embedded portion 82 formed so as to be held by a rotor, and a blade portion 85 is formed, with a shank 83 and a platform 84 being disposed between the embedded portion 82 and the blade portion 85. In the gas turbine moving blade 81, a hollow passage into which a cooling medium is to be introduced is formed, and a cooling medium inflow port 86 communicating with the passage is formed at a bottom surface of the embedded portion 82.
In a flow rate measuring device 90, a box body 87 is provided for supplying air to the gas turbine moving blade 81, and the gas turbine moving blade 81 is fixed by a hold-down jig 91, with the cooling medium inflow port 86 of the embedded portion 82 in alignment with a supply port 88 of the box body 87. A sealing plate member (a rubber hold-down plate) 89 made of rubber or the like is provided between the supply port 88 and the cooling medium inflow port 86 of the embedded portion 82. A hole of the same shape and at the same location as the cooling medium inflow port 86 is formed in the rubber hold-down plate 89.
The gas turbine moving blade 81 is mounted on the flow rate measuring device 90, and air or the like is supplied to the cooling medium inflow port 86 through the supply port 88 of the box body 87. The air or the like is flowed through a passage inside the gas turbine moving blade 81 so that the flow rate of the air or the like is measured. By this means, it is evaluated whether a predetermined amount of the cooling medium is flowing through the passage of the gas turbine moving blade 81. The air supplied to the cooling medium inflow port 86 through the supply port 88 is kept by the rubber hold-down plate 89 from leaking out.
With the conventional measurement of the flow rate in the gas turbine moving blade 81, the sealing plate member (rubber hold-down plate 89) made of rubber or the like is used to prevent leakage of air to the outside, without interruption of the flow of air. If misalignment occurs during mounting, however, the hole of the rubber hold-down plate 89 may interfere with the cooling medium inflow port 86, partially blocking the cooling medium inflow port 86.
If the cooling medium inflow port 86 is partially blocked, the amount of air flowing into the passage through the cooling medium inflow port 86 may vary, causing an error in the measured value of the flow rate, thereby making the accurate determination of the flow rate impossible.